This invention relates, in general, to dispensing devices and, in particular to a new and useful metering pump having two telescopically movable parts, one of which defines an inlet connected to a bellows which has an opposite end connected to the other part which has a delivery passage.
The invention relates, particularly, to a metering pump for the delivery of metered quantities of liquid and/or low-viscosity, in particular pasty, media from bottles, cans or the like. A bellows of flexible plastic is arranged in a sealing between two axially telescopically movable housing parts of dimensionally stable plastic. Both ends of the bellows pump have valves which in each case have a closer member which is movable axially relative to a valve seat ring surface. The valve seat ring surface on the intake side is molded onto the bellows and the first housing part is provided with a delivery mouthpiece and the second housing part is capable of being fitted on the neck of a bottle, can or the like or being provided with a molded-on container.
In the case of a known, manually operated bellows spray pump (German patent No. 2,842,073) for a liquid media, the end section on the discharge side, which forms the last fold, is clamped fixedly between two interlocking housing parts. The end section on the delivery side of the bellows, which is provided with an intake extension in the form of a hose and with a conical valve seat annular surface for a ball as closing member, is seated positively fixed in an axially movable tensioning and compressing member, which is under the effect of a compression spring acting in delivery direction. For the intake of liquid from a container, the bellows must be stretched axially with simultaneous tensioning of the compression spring.
Thereafter, the compression spring exerts a constant delivery pressure on the bellows. As a delivery device, a spray nozzle is arranged at the end of a spring-loaded tube nipple which is axially movable in an end wall of a housing part. The tube nipple has a flange ring and, outside thereof, a transverse bore which can be closed by a ring seal and becomes free when the tube nipple is pushed into the end wall. Apart from the fact that, with this device, only a liquid medium, not metered quantities, can be delivered, the structure and mode of operation is much too complex and elaborate for mass production. This device is not suitable for the delivery of pasty media, because the pump valve on the delivery side has an only very small passage cross-section.
In the case of another known metering pump with pump bellows (German patent No. 3,509,178) the two mutually axially displaceable housing parts are in each case provided with a transverse wall running at right angles to the axis of the bellows. These transverse walls have in each case on the sides facing each other annular ribs each for the sealing reception of a bellows. In addition, bores with a valve seat ring surfaces and the associated closing members of the pump valves are arranged in these two transverse walls. While the transverse walls of the housing part provided with the delivery mouthpiece is provided with a tube socket protruding into the bellows, for guidance of the closing member of the pump valve on the delivery side, the transverse wall of the second housing part has a tube socket arranged on the side opposite the bellows for guidance of the closing member of the pump valve on the intake side. At the same time, this tube socket is provided with a socket of tapered diameter for the fastening of intake hose. Both housing parts are provided with cylindrical guide walls which fit telescopically one in the other, the second housing part being provided in the region outside the transverse wall with an internal thread by which it can, for example, be screwed onto the external thread of a bottle neck or a can neck.
While the closing member of the pump valve on the intake side is accommodated loosely in the tube socket of the transverse wall of the second housing part by means of annular ribs arranged in star shape and is secured against falling out by claw-like fingers protruding into the inside of the bellows, the closing member of the pump valve on the delivery side has molded-on spring members which push it with slight axial pressure on the valve seat ring surface and hold it in closed position. These spring elements are supported on an end wall of the housing part provided with the delivery mouthpiece. In order to bring this closing member into its working position, it is necessary that this first housing part is provided with a removable or subsequently attachable end wall, for the attachment of which a special operation is necessary in each case.